Megalac – digestibility
Megalac has a proven high digestibility, likely reflecting the balance of saturated and unsaturated fatty acids the product contains, in particular the concentration (36%) of oleic acid (C18:1), a known amphiphile, which can promote the digestibility of total fat in the diet. Several studies with lactating dairy cows have reported digestibility values of over 90%.
In a study at Ohio State University, USA, high yielding dairy cows were offered a control diet, or the control diet supplemented with Megalac (at either 1.75% or 3.4% of DM) or hydrogenated triglycerides of palm in a Latin square design (Weiss and Wyatt, 2004).
As presented in Table 1, digestibility of Megalac was high (92.9%) at the more-typical on-farm feed level of 1.75% of DM (equating to approx. 400 g Megalac/d), and 87.5% at the much higher feed level (equating to 750 g Megalac/d). These data also demonstrate the effect of Megalac on total diet fat digestibility with an improvement of up to 9.8% recorded, resulting in increased energy availability and feed efficiency.
This improvement in total diet efficiency likely reflects the high concentration of the C18:1 (oleic acid) in Megalac which is known to act as an amphiphile, increasing micelle formation and digestibility of the more-saturated fatty acids in the diet.
Table 1 Digestibility of Megalac offered at 1.75 and 3.4% of diet DM
|Megalac (% DM)||Hydrogenated triglycerides (% DM)|
|Fat supplement digestibility (%)||-||92.9||87.5||39.0||38.1|
|Total diet fat digestibility (%)||73.7||80.2||80.9||61.7||54.8|
Weiss, W.P. and Wyatt, D.J., 2004. Digestible energy values of diets with different fat supplements when fed to lactating dairy cows. J. Dairy Sci. 87, 1446–1454
Recognising that many factors can impact fat digestibility across different experiments, Drackley (1999) compiled ‘standardised’ digestibility values obtained in his own experiments for several fat sources, including Megalac.
Table 2 presents data on digestibility of Megalac recorded at 3, 6 or 9% inclusion levels in the diet DM.
Table 2 Digestibility of Megalac recorded in published studies
|Expt no.||Inclusion rate (% DM)||Standardised digestibility|
These data indicate a digestibility of Megalac of around 96% at the inclusion level closest to more typical feed levels (2-3%). However, even at much higher levels of inclusion digestibility remains high, averaging 81.8% at 6% level of inclusion.
Drackley, J.K. (1999). New perspectives on energy value and supplementation levels of supplemental fats. Advances in Dairy Technology : Proceedings of the Western Canadian Dairy Seminar, 171-184.